Green’s Dictionary of Slang

dead set phr.

[dead set adj.]
(Aus.)

1. a phr. denoting acquiescence, ‘that’s fine’.

[Aus]D. Ireland Glass Canoe (1982) 62: ‘I’ll give you the drum.’ ‘Dead set.’.
[Aus]Lette & Carey Puberty Blues 9: Here yar. Have me lunch. Dead-set, I’m not hungry.
[Aus]R.G. Barrett You Wouldn’t Be Dead for Quids (1989) 150: ‘Some of these blokes wouldn’t get a ride on a ghost train’ ‘Dead set?’ ‘Dead set, Les’.

2. a general negative phr.

[Aus]Lette & Carey Puberty Blues 84: Oh deadset. I’m not gunna walk all the way.
[Aus]Bug (Aus.) 16 Aug. [Internet] We have grown accustomed to the faces of rugby league spreading bullshit thicker than a National Party supporter growing a crop of grass. But deadset, just how much room is there up Kneel WitLacker’s arse?